Urban pointed out that biological systems that can repair themselves may do so by either visible or invisible means. "Some we can see, like the skin healing and new bark forming in cuts on a tree trunk," he said in a press release.
"Some are invisible, but help keep us alive and healthy, like the self-repair system that DNA uses to fix genetic damage to genes."
The team, at the University of Mississippi's Urban Research Group, has worked on similar technology for several years. It has developed plastics with small molecular links that span the long chains of polymer's component chemicals.
The links break and change shape when the polymer is scratched or cracked. Modifying the links resulted in a visible color change when they change shape, forming a red blotch around the defect. (Watch a video of an accelerated similar self-repairing process, which doesn't change color first, here
.) The links reform when temperature or pH changes, or when in the presence of ordinary sunlight or visible light from a light bulb.
Urban said that automobile fenders made of the new material that have become scratched could be repaired by being exposed to intense light. Structural components of aircraft could turn red where they have become cracked as a warning of damage. That would give engineers the choice of fixing the damage or completely replacing the component. He also cited several applications for battlefield weapons systems.
The team, which received funding for the project from the US Department of Defense, is currently working on incorporating the technology into plastics that can withstand high temperatures.